[GRASS-user] Why r.watershed Yields Narrow Basins

[Markus Metz]

On Sat, Jun 9, 2012 at 6:38 PM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Sat, 9 Jun 2012, Margherita Di Leo wrote:
>
>> Try also multiple flow direction (MFD) algorithm ( -f  flag in
>> r.watershed)
>
>
> madi,
>
>  That was much worse. The basins were even less realistic. I also tried the
> -4 option, but that made rectangular basins. I thought the MFD would produce
> better results than the SFD, but apparently not; at least, in this one
> situation.

These nearly straight red lines indicate that the DEM is flat in these
areas. What kind of pre-processing did you apply? Also, to reproduce
the results, the output of r.info of the DEM, g.region and g.proj
would be helpful.

Markus M